A Push-To-Talk (PTT) server may be used to provide voice features. A traditional system that provides the PTT functionality may be performed over a communication network such as a Long Term Evolution (LTE) network. In such a system, only a single, controlling PTT server controls a particular group session of a PTT communication group that includes a plurality of mobile units (MUs). The controlling PTT server is configured to involve the MUs that belong to the controlling PTT server as well as MUs that belong to other (i.e., participating) PTT servers. The MUs that belong to, and operate in a coverage area of, the controlling PTT server may directly connect to the controlling PTT server for control messaging and media that is sent by unicast. The MUs that belong to, and operate in coverage areas of, other (participating) PTT servers may indirectly receive the control messaging and media, which is sent by unicast through the other PTT servers and which other PTT servers are connected to the controlling PTT server via a network-to-network interface (NM).
Similarly, for media broadcasts, the MUs that belong to the controlling PTT server and that operate in a Multicast Broadcast Single Frequency Network (MBSFN) area of an operating area of the controlling PTT server may again directly connect to the controlling PTT server for receipt of the media broadcasts. Specifically, the Multimedia Broadcast Multicast Services (MBMS) operating area may define at least one MBSFN area which provides a respective communication channel that may be configured for the group session of the PTT communication group. And the MUs that belong to other (participating) PTT servers and that are disposed within an operating area (or MBSFN area of that operating area) of the other PTT servers indirectly receive the media broadcasts from the controlling PTT server through the other PTT servers.
When MBMS support is required for the MUs that belong to the controlling PTT server but operate in an MBSFN area of one of the other PTT servers, the other PTT server serving the MBSFN area is required to provide MBMS support for these MUs. However, for the other PTT server to provide the MBMS support for these MUs, at least one MU included in the group session of the PTT communication group must belong to the other PTT server. That is, if at least one MU that is part of the group session belongs to the other PTT server, then an MU that belongs to the controlling PTT server but that operate in the MBSFN area of the other PTT server is capable of being provided the MBMS support by the other PTT server. However, if no MU that is part of the group session belongs to the other PTT server, then an MU that belongs to the controlling PTT server that operate in a MBSFN area the other PTT server might not be provided MBMS support, as the other PTT server is not associated with the group session. That is, the other PTT server, having no MUs that belong to the group session, is unaware of the group session as well as any MU belonging to the controlling PTT server that may operate in an MBSFN in its operating area.
Accordingly, there is a need for providing MBMS support for MUs that are participants of a group session of a PTT communication group belonging to the controlling PTT server but that are operating in a MBSFN area of an operating area of an unaware, other PTT server.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.